可变扩频增益CDMA系统的功率速率联合控制

Integrated power and rate control in variable spreading gain CDMA systems

为了使移动通讯系统获取最大容量,针对可变扩频因子码分多址接入(CDMA)系统,给出了一种基于信干比(SIR)平衡的功率速率联合控制方案.该方案根据反馈的SIR动态地改变数据的速率和功率,其中功率控制优先于速率控制,当信道变化缓慢时,数据率保持在一个相对稳定的值上,调节发射功率来维持SIR平衡;当功率调节无法弥补信道的衰落时,则通过调节速率来维持SIR的平衡.仿真和分析结果显示,功率速率联合控制的方案显著地提高了系统的性能;参与判断改变数据速率的时隙数目的选取应针对不同的信道衰落环境来设置.

To minimize the effect of multi-access interference, joint transmitting power and data rate control was used for data service. Variable spreading gain CDMA (code division multiple access) system is a candidate system that accommodates mixed traffic types, and supports variable data rate service. An integrated power and rate control scheme was proposed, based on SIR (signal to interference ratio) balancing in this kind of CDMA systems. In this scheme, power control is primary to the rate control. With the slowly changed fading channel, the transmitting data rate keep on an appropriate level, and only the power control works to keep up with the channel fading and balances the SIR. But when the channel quality is poor, the data rate switches down without sacrificing the BER (bit error rate); otherwise high data rate is selected. The simulation results of uplink show that the scheme achieves a good system performance and the number of slots should be determined with respect to the variation speed of the fading channel.